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1.
Recombinant Japanese eel follicle-stimulating hormone (rjeFSH) produced by methylotrophic yeast was subjected to in vivo bioassay to assess its gonadotropic activities and availability to artificially induce maturation of this species. Intramuscular injections of rjeFSH into male eels at doses of 0.1 and 1.0 U/g body weight were repeated 3 times during 12 days. The rjeFSH significantly increased plasma 11-ketotestosterone levels, and induced both testicular growth and spermatogenesis in a dose-dependent manner. These results demonstrate that rjeFSH is effective in promoting male eel gamatogenesis in vivo. Instead of scarce native eel FSH, abundant recombinant eel FSH is now ready for future application to maturation induction of Japanese eel. 相似文献
2.
H. Asanuma H. Ohashi H. Matsubara S. Ijiri T. Matsubara T. Todo S. Adachi K. Yamauchi 《Fish physiology and biochemistry》2003,28(1-4):383-384
Isolated hepatocytes from male Japanese eel at various stages of human chorionic gonadotropin (HCG)-induced spermatogenesis were cultured in the presence of estradiol-17β (E2). Hepatic vitellogenin (VTG) production in response to E2 increased during testicular development. This indicates that VTG production is influenced by gonadal maturity not only in females but also in males, where serum levels of 11-ketotestosterone (11KT) increase during testicular development. Recently, it has been confirmed that significant levels of 11KT are detected in maturing female eel. Therefore, in a next experiment, effect of 11KT on E2-induced VTG production was examined in vitro. As a result, in both male and female hepatocytes, 11KT enhanced E2-induced VTG production, although 11KT alone failed to induce VTG production. 相似文献
3.
外源性促性腺激素诱导日本鳗鲡精子发生和成熟的作用机制 总被引：2，自引：0，他引：2
用兔抗血清对抗促黄体素生成素受体（LHR）或称绒毛膜促性腺激素受体（CGR）和雄激素受体（AR）进行LHR和AR免疫组织化学定位,以揭示外源性促性腺激素（鲤脑垂体激素和hCG）诱发日本鳗鲡精子发生及其内分泌机制。结果表明,经过注射激素处理后的实验组与注射前的对照组相比较,其精巢发育和精子发生出现十分显著的变化。组织学切片观察显示,激素处理前鳗鲡精巢处于精原细胞增殖期,而两种激素混合注射后第10天,实验组可见精小叶中精原细胞的有丝分裂和初级与次级精母细胞的数量显著的增加。注射后第35天,靠近生殖上皮除有少量精原细胞外,精小叶中有大量初级精母细胞和次级精母细胞和少数精子细胞以及管腔中存在少量精子。在注射后第83天,日本鳗鲡完成了精子发生和精巢发育成熟以及释精。免疫组织化学染色结果进一步揭示,激素处理前,LH受体免疫活性分布在生殖上皮,显示强的免疫阳性反应;激素处理后,LH受体定位在Sertoli细胞和间质细胞以及精原细胞和初级与次级精母细胞的胞膜上,均显示强的免疫阳性反应。激素处理前,雄激素受体定位在生殖上皮和早期生精细胞的胞膜上;激素处理后,AR则定位在这些生精细胞的核或胞质,而精子细胞和精子显示免疫阴性反应。这些结果首次证明了这两种激素诱导鳗鲡精子发生和成熟的作用机制是通过LH受体和雄激素受体的介导。 相似文献
4.
The initial appearance and the development of Leydig cells (LCs), the sites of steroid hormone production in the testis, were investigated ultrastructurally during testicular differentiation in the Japanese eel, Anguilla japonica. In addition, the effects of a single injection of human chorionic gonadotropin (HCG; 5 IU g body weight-1) on histological changes of the testes and serum 11-ketotestosterone (11-KT) were examined at various stages (15–18, 20–23, 26–29, 32–35, 38–41 and 46–50 cm body length (BL)) of testicular differentiation. Testicular differentiation was morphologically characterized by the development of loose connective tissue on the medial side in animals 18–29 cm in BL. Ultrastructurally, LCs were first identified in the loose connective tissue of the testis of the 23 cm fish. In the testes of fish over 32 cm, clusters of LCs were distributed throughout the interstitial region accompanying the increase in number of spermatogonia. In fish larger than 32 cm, spermatogenesis was induced by administration of HCG; serum 11-KT levels were also raised. On the other hand, there was no effect on spermatogenesis or serum 11-KT levels in fish less than 29 cm, or in the controls. These result suggests that morphological differentiation of LCs occurs in testis of the 23 cm eel, and subsequently, the testes of eels of BL more than 32 cm acquire the capability to produce steroid hormones. 相似文献
5.
为证明日本鳗鲡(Anguilla japonica)生活史最后一步一产后鳗的命运,本研究模拟产后的日本鳗鲡继续在海水中养殖,观察其存活率及繁育情况.结果表明,产后鳗在海水中停食约18 d后,体能得到恢复,部分亲鱼开始出现摄食,1个月左右全部恢复摄食,经244 d养殖,雌、雄鳗体质量增加,存活率达94.6%.随后,给产后鳗注射外源性促性腺激素(鲤鱼脑垂体匀浆CPE和人绒毛膜促性腺激素HCG)后激发其退化的性腺(卵巢和精巢)重新发育(与当年银鳗作对照).通过性腺组织切片观察产后鳗和对照鳗性腺发育成熟的全过程及其差异,发现产后鳗起初性腺发育比当年银鳗差,但经多次注射激素后,产后鳗性腺成熟与当年银鳗同步,证明产后鳗生殖细胞对激素的敏感件高.应用17α,20β-双羟孕酮和促性腺激素释放激素类似物(GnRH-A3)使催熟的产后鳗和对照鳗均产卵和排精,并孵化出仔鱼,从而有力地证明,鳗鲡产后虽体质弱,但待体能恢复后能够继续生存和繁殖.本研究旨在探讨利用产后鳗作为今后鳗鲡人工繁殖亲鳗的可行性. 相似文献
6.
H. Svedng 《Fisheries Research》1999,40(3):616-265
The population dynamics and exploitation of the yellow eel (Anguilla anguilla (L.)) stock on the Swedish west coast were studied. In contrast to a generally observed reduction in the recruitment of glass eels in Europe, including in Swedish waters, there was no indication of a decline in the total eel fishery yields along the Swedish west coast. Long-term records of daily catches as well as by test fishing results also shown that this stability in eel fishery yields has not been maintained by an increase in fishery effort, as the catch-per-unit-efforts in the past 20 years have been more or less unchanged. These findings implied that the number of recruits to the fishery has been rather stable, possibly indicating that density-dependent factors at the elver and yellow eel stages may moderate variations in glass eel recruitment. Total instantaneous rate of mortality was estimated from records on eel length distribution in the professional fyke-net fishery. The estimated total mortality rate in an isolated archipelago population on the west coast was chosen as an approximation of the instantaneous rate of natural mortality and net emigration in the west coast eel stock. The differences between these two estimates could, thus be regarded as the mortality that occurred due to fishing. It was found that the eel fishery was very intense and most fish were caught in small sizes, resulting in a low escapement rate of maturing fish. 相似文献
7.
《Aquaculture (Amsterdam, Netherlands)》2005,243(1-4):393-402
To investigate whether steroid profiles in salmon pituitary homogenate (SPH)-induced artificially maturing Japanese eel, Anguilla japonica, resemble those in other, naturally maturing fishes, the daily changes in 11 steroids were analyzed for a 70-day period (average time needed to reach the maturational phase). Concentrations of most steroids were low and changed on a weekly basis, with maximum values 2–5 days after an SPH injection. Thus, pregnenolone, 17α-hydroxypregnenolone, dehydroepiandrosterone, progesterone, 17α-hydroxyprogesterone, 17α,20 β-dihydroxy-4-pregnen-3-one, androstenedione and estrone levels were barely or not detectable in serum throughout the experimental period, which is largely in keeping with what is known about oogenesis-related steroids in other fishes. In contrast, serum testosterone (T) levels were high, but fluctuated considerably with each SPH injection (about 0.3–8.3 ng/ml). The serum estradiol-17β (E2) levels increased after SPH injections and gradually rose throughout the experiment, peaking at the end of the experimental period (about 0.2–7.8 ng/ml). Serum levels of 11-ketotestosterone (11-KT) before SPH treatment were higher (approximately 2 ng/ml) than those of the other steroid hormones (less than 0.5 ng/ml). 11-KT levels increased gradually over the experimental period, and, like E2, levels peaked towards the end of the experimental period (about 15 ng/ml). The observed patterns for T, E2 and 11-KT are unlike those in other fishes. Furthermore, the consistent elevations in levels of 11-KT, both before and after SPH treatment, are suggestive of an important role for this steroid in controlling oocyte growth. 相似文献
8.
M. Matsubara P.M. Lokman A. Senaha Y. Kazeto S. Ijiri A. Kambegawa T. Hirai G. Young T. Todo S. Adachi K. Yamauchi 《Fish physiology and biochemistry》2003,28(1-4):353-354
The control of 11-ketotestosterone (11-KT) biosynthesis and its physiological roles were examined in female Japanese eel (Anguilla japonica) and New Zealand longfinned eel (Anguilla dieffenbachii). 11-KT was detected in serum of female eels of both species. Among various tissues from Japanese eel, the ovary had the greatest capacity to synthesize 11-KT in vitro. In addition, the oocyte diameters of eels treated with 11-KT had increased significantly. Furthermore, these oocytes were found to have an increased number of oil droplets. These findings suggest that 11-KT in female eels may be mostly of ovarian origin and that this androgen appears to play an important role in controlling pre-vitellogenic oocyte growth. 相似文献
9.
R. G. J. M. Hanssen N. Mayer-Gostan G. Flik S. E. Wendelaar Bonga 《Fish physiology and biochemistry》1993,10(6):491-496
The kinetics and hypocalcemic potency of stanniocalcin (STC) were examined in freshwater and seawater eels. The secretion rate and the metabolic clearance rate of STC were calculated from the STC disappearance curve after intra-arterial injection of trout STC. Basal plasma STC concentrations in freshwater and seawater eels did not differ but the STC secretion rate and metabolic clearance rate in seawater eel were 70–75% higher than in FW eel. The increased STC distribution space in seawater eels suggests that the STC receptor density was increased. STC had a higher hypocalcemic potency in seawater than in freshwater eels. These observations support the hypothesis that seawater fish require more hormonal control over transcellular influx of calcium than freshwater fish.To whom correspondence should be addressed. 相似文献
10.
Comparison of glass eel stages of American eel and speckled worm eel in a northeast Florida estuary 
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下载免费PDF全文 K. I. Bonvechio 《Fisheries Management and Ecology》2016,23(5):350-355
Since 2001, a glass American eel, Anguilla rostrata (Lesueur), survey has been conducted at Guana River Dam, Florida, USA. Although present in earlier samples, glass speckled worm eel, Myrophis punctatus Lütken, were not identified until a large proportion appeared in samples in 2006. To determine whether the species could be separated in historical samples, weight–length relationships were compared between the two species. Then, with data from the full survey period, relationships between catch rate and annual percent contribution of glass speckled worm eel were explored in relation to temperature, water flow and salinity. Glass speckled worm eel were found to weigh significantly less and had distinguishing physical characteristics that could be used for identification. Glass speckled worm eel constituted between 0 and 34% of the catch, with no detectable pattern in timing or abundance among years. In 2006 and 2012, which had the two largest catches of glass speckled worm eel, relationship between nightly catch rate and measured environmental variables was inconsistent, even when measured variables had a similar range in values. It is recommended that south‐eastern, including Gulf of Mexico, USA, states restrict harvest of glass American eel to prevent the incidental capture and exportation of glass speckled worm eel. Efforts should be made to ensure proper species identification in glass eel surveys. 相似文献
11.
12.
Jie Mei Wei Yan Jie Fang Gailing Yuan Nan Chen Yan He 《Fish physiology and biochemistry》2014,40(4):1181-1190
In vertebrate species, the biopotential embryonic gonad differentiation is affected by many key genes and key steroidogenic enzymes. Insulin-like growth factor-1 receptor (Igf1r) has been considered as an important sex-differentiation gene in mammals and could mediate the biological action of Igf1, an important regulator of key steroidogenic enzymes. However, Igf1r gene is still unknown in the swamp eel, an economically important fish. In our study, we identified Igf1r gene in the swamp eel, which was a 2,148-bp open-reading frame encoding a protein of 716 amino acids. The alignment and the phylogenetic tree showed that Igf1r of the swamp eel had a conservative sequence with other vertebrates, especial fishes. Western blotting of Igf1r showed that Igf1r expressed much more in ovotestis and testis than in ovary, indicating an important role of Igf1r during gonad differentiation. We analyzed ubiquitination of Igf1r by co-immunoprecipitation and found the amount of ubiquitinated Igf1r was increased from ovary, ovotestis to testis, which was reversely to the trend of Hsp10 expression during gonadal transformation. It was possible that Hsp10 could suppress Igf1r ubiquitination during gonadal development of the swamp eel. 相似文献
13.
Histochemical localization of proteolytic activities in the dorsal epidermis of Japanese eel was demonstrated by fluorescent microscopy utilizing 4-methoxy-2-naphthylamide (4M$\beta$NA) derivatives as substrates and 5-nitrosalicylaldehyde as a trapping agent. Carbobenzoxy-L-phenylalanyl-L-arginyl-4M$\beta$NA (Cbz-Phe-Arg-4M$\beta$NA) and Cbz-Arg-Arg-4M$\beta$NA were used for direct detection of cathepsins L and B activities, respectively, in fresh frozen sections and unfixed cells of the eel epidermis. The fluorescing areas, where Cbz-Phe-Arg-4M$\beta$NA was hydrolyzed by cathepsin L, were shown in mucus secretory cells and club cells and broadly around skin surface. The fluorescing areas due to Cbz-Arg-Arg-4M$\beta$NA hydrolysis by cathepsin B were localized similarly in these tissues. The fluorescing intensity for both catheptic activities in mucus secretory cells was higher than that in club cells, where small fluorescing granules were distributed. These results indicate that eel cathepsins L and B are stored in epidermal secretory cells at different levels and probably serve as defense factors before or after secretion by these cells. Abbreviations: Cbz – carbobenzoxy; 4M$\beta$NA – 4-methoxy-2-naphthylamide; NSA – 5-nitrosalicylaldehyde. 相似文献
14.
Youichi Hayakawa Hidekazu Nagaya Hiroki Kaki Komei Hotta Makito Kobayashi 《Fisheries Science》2009,75(1):137-144
We previously demonstrated the biological activities of single-chain recombinant gonadotropins (scGTHs) of goldfish Carrassius auratus follicle-stimulating hormone (scFSH) and luteinizing hormone (scLH), produced by a baculovirus–silkworm larvae system, by
using in vivo bioassays with some fishes including Japanese eel Anguilla japonica. Among the bioassays, we succeeded in induction of spermatogenesis of sexually immature male Japanese eels by both scFSH
and scLH, especially resulting in the occurrence of spermatozoa in scLH-administered males. However, those recombinant hormones
did not induce enlargement of testes. In order to further confirm the potency of recombinant GTHs for use in aquaculture species,
we administered scFSH and scLH to males of Japanese eel at higher dosage and frequency (eight times with 2–5 days interval)
than those of the previous study (five or six times with 7 days intervals), including combination of scFSH and scLH administration
(scFSH–scLH). Gonadosomatic indices (GSI) of scLH- and scFSH–scLH-administered males were larger than those of initial control
males and of control males that were injected with saline. Enlargement of testes was also confirmed by measurement of testicular
lobe size in scFSH-, scLH-, and scFSH–scLH-administered males. By histological observation, occurrence of spermatozoa was
confirmed in scLH- and scFSH–scLH-administered eels. Although milt production was not induced, higher dosage and frequency
of scGTH administration was effective in promoting testicular development of immature eels. Thus, single-chain fish GTHs produced
by the baculovirus–silkworm larvae system could be a useful tool for promotion of gonadal maturation in aquaculture fishes. 相似文献
15.
The first success of glass eel production in the world: basic biology on fish reproduction advances new applied technology in aquaculture 总被引：1，自引：0，他引：1
Hirohiko Kagawa Hideki Tanaka Hiromi Ohta Tatsuya Unuma Kazuharu Nomura 《Fish physiology and biochemistry》2005,31(2-3):193-199
The eel has long been esteemed as an important food fish in the world, especially in Japan, and has been used as an experimental
fish for many fields of fish physiology. However, the decreases in eel resources have been a serious concern in recent years.
The catches of glass eels as seedlings for aquaculture have shown a long-term decrease in both Europe and East Asia. To increase
eel resources, the development of techniques for artificial induction of maturation and spawning and rearing their larvae
have been eagerly desired. Recent progress of reproductive physiology of fish, especially mechanisms of oocyte maturation
and ovulation in female and of spermatozoa maturation in male, facilitate to establish techniques for hormonal induction of
maturation and spawning in sexually immature eels. With persistent effort to development of rearing techniques of larvae,
we have first succeeded to produce glass eel. These applied techniques are may contribute to understand the basic reproductive
physiology of the eel. 相似文献
16.
Growth hormone (GH) secretion from organ-cultured pituitaries of the eel (Anguilla japonica) was studied during incubation in a defined medium for 2 weeks, using a homologous radioimmunoassay which does not distinguish
between the two molecular forms of eel GH. The total amount of GH secreted increased gradually during the incubation period;
so that the amount of GH released on day 14 was about 30 times greater than that on day 1. On day 14, the proportion of GH
released relative to the total amount of GH present (the sum of GH released into the medium and residual content in the pituitary)
was 96% and the amount produced on day 14 was 4 times greater than the content in the unincubated pituitary. Somatostatin
(SRIF, 1.8 × 10-7 M) inhibited the increase in GH release. On day 7, the proportion of GH released by pituitaries treated with SRIF (28%) was
less than that released by the control pituitary (91%). There was no significant difference in GH release between the pituitaries
incubated in isotonic medium (300 mOsm) and those in hypotonic medium (240 mOsm) for 2 weeks except for the first 3 days,
when the pituitaries in hypotonic medium secreted significantly greater amounts of GH than those incubated under isotonic
condition. Hypertonic medium (350 mOsm) had no effect on GH release except for significant inhibition on days 6 and 14. When
secretion of the two forms of GH (GH I and II) was examined after separation by polyacrylamide gel electrophoresis followed
by densitometry, slightly more GH I tended to be secreted than GH II during the culture period, although the effects of SRIF
and osmolality of the media on GH I release were similar to those on GH II. It is concluded that GH secretion and production
in the eel is mainly under the inhibitory control of hypothalamus, and that osmolality has a minimum influence on the GH release. 相似文献
17.
Shigeho Ijiri Norio Takei Shinji Andachi Kohei Yamauchi 《Fish physiology and biochemistry》2003,28(1-4):209-210
Antibodies against P450scc, P450c17 and P450arom were generated using recombinant proteins. In eel testis, P450scc and P450c17 were immunolocalized as clusters in Leydig cells. In vitellogenic eel ovary, P450scc and P450c17 immunoreactive cells were localized as clusters in the outer layer of the ovarian follicle. In contrast, P450arom seemed to be immunolocalized in the innermost follicle layer. 相似文献
18.
ABSTRACT: Cultured immature female Japanese eels acclimated to sea water at either 10 or 20°C were treated weekly with salmon gonadotropin fraction (sGTH) in order to investigate the effects of water temperature on artificial induction of ovarian maturation. In eels maintained at 20°C, ovulation was induced in 11 of 18 fish during the experimental period of 13 weeks, whereas at 10°C all fish showed a low gonadosomatic index (GSI) at the end of the experiment. Plasma vitellogenin levels were higher in eels kept at 20°C than in eels at 10°C throughout the experiment. However, no significant differences were observed in the plasma testosterone and estradiol-17β levels between groups. Eels pretreated with sGTHs at 10°C for 13 weeks were separated to two different temperature (10 and 20°C) groups, and received the same weekly sGTH injections. In eels transferred to 20°C, plasma vitellogenin levels, GSI and oocyte diameter were increased, but these values were maintained at low levels in eels that remained at 10°C. These results clearly indicate that water temperature is an important factor regulating vitellogenesis in the Japanese eel. 相似文献
19.
D. Buysse A. M. Mouton M. Stevens T. Van den Neucker J. Coeck 《Fisheries Management and Ecology》2014,21(1):13-21
Although numerous pumping stations (PS) have been used by water managers for numerous applications on rivers, canals and other water bodies, their impact on fish populations is poorly understood. This study investigates European eel, Anguilla anguilla (L.), mortality after natural downstream passage through a propeller pump and two Archimedes screw pumps at two PSs on two lowland canals in Belgium. Fyke nets were mounted permanently on the outflow of the pumps during the silver eel migration periods. Based on the condition and injuries, maximum eel mortality rates were assessed. Mortality rates ranged from 97 ± 5% for the propeller pump to 17 ± 7% for the large Archimedes screw pump and 19 ± 11% for the small Archimedes screw pump. Most injuries were caused by striking or grinding. The results demonstrate that PSs may significantly threaten escapement targets set in eel management plans. 相似文献
20.
Marian Leopold 《Aquaculture (Amsterdam, Netherlands)》1980,19(1):97-101
The paper presents basic factors determining eel production in Polish lakes. Analysis of data from 582 lakes over 29 years (1950–1978) showed that ell yield in lakes is basically determined by the artificial stocking of eels. The relationship between eel catch and eel stocking is very close and to a certain extent independent of the fishing effort. Prospects of further development of eel management in Europe are presented, as well as basic problems facing this management on a general scale. A need is identified for further studies in this field. 相似文献